CVE-2025-38433

Medium

In the Linux kernel, the following vulnerability has been resolved: riscv: fix runtime constant support for nommu kernels the `__runtime_fixup_32` function does not handle the case where `val` is zero correctly (as might occur when patching a nommu kernel and referring to a physical address below the 4GiB boundary whose upper 32 bits are all zero) because nothing in the existing logic prevents the code from taking the `else` branch of both nop-checks and emitting two `nop` instructions. This leaves random garbage in the register that is supposed to receive the upper 32 bits of the pointer instead of zero that when combined with the value for the lower 32 bits yields an invalid pointer and causes a kernel panic when that pointer is eventually accessed. The author clearly considered the fact that if the `lui` is converted into a `nop` that the second instruction needs to be adjusted to become an `li` instead of an `addi`, hence introducing the `addi_insn_mask` variable, but didn't follow that logic through fully to the case where the `else` branch executes. To fix it just adjust the logic to ensure that the second `else` branch is not taken if the first instruction will be patched to a `nop`.

Package Linux Kernel
Published 2025-07-25
Last modified 2025-11-19
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-476

CVE-2025-38433 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.15 and later are affected. Fixed in 6.15.5, 6.16 and their respective stable series.

Affected from
≥ 6.15
Fixed in
✓ 6.15.5 6.15.x ✓ 6.16

References

The following references provide additional information about CVE-2025-38433 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Frequently asked questions

  • What is CVE-2025-38433?

    CVE-2025-38433 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 6.15 onward and has been patched in 6.15.5 and 6.16. CVE-2025-38433 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-38433?

    CVE-2025-38433 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2025-38433?

    Yes — CVE-2025-38433 has been patched. Fixed versions include 6.15.5 and 6.16. If you are running Linux kernel 6.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-38433 actively exploited?

    No — CVE-2025-38433 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is NULL Pointer Dereference (CWE-476)?

    The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. View CWE-476 on MITRE CWE →

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